1. Field of the Invention
This invention relates generally to coking oven charging systems, and more particularly to a coking oven charging system employing an improved connecting means for forming a substantially gas-tight connection with a charging hole or port in the top wall of a coke oven to substantially reduce emissions during charging.
2. Description of the Prior Art
Coke ovens of the type employed in the production of metallurgical coke used, for example, in the production of iron and steel are generally of the regenerative or by-product recovery type and are constructed in batteries consisting of a number of transversely-extending coking chambers or ovens and heating flues or chambers arranged alternately along the length of the battery. The ovens and heating chambers are constructed of or lined with heat resistant refractory material and have a continuous top wall extending over the entire battery. The individual ovens are charged through a plurality of normally-closed charging holes extending through the top wall and arranged at spaced intervals along the length of the individual ovens. Coal is charged into the ovens from hoppers carried by a larry car running on rails or tracks extending along the top wall of the battery.
To charge an oven, the larry car is positioned with the coal hoppers located directly above the charging holes in the oven. The charging hole covers or lids are removed and charging pipes at the bottom of the hoppers are brought into registry with the top rim of the respective charging holes. The bottom of the hoppers are then opened, permitting finely crushed coal to flow by gravity directly into the hot coking chamber. This produces a surge of gas from the chamber due both to the displacement of the furnace gas by the large volume of coal and to the generation of additional gases by the vaporization of moisture in the coal and the initial burning and volatization of the newly-deposited coal. This surge of gas during charging is referred to herein as charging gas to distinguish from the gases normally evolved during the coking process.
Regenerative, or by-product ovens are conventionally fitted with aspiration or ascension pipes connected to a large collecting main extending the length of the battery and leading to a by-product recovery plant. During the coking cycle, the distillation products evolved in the ovens flow through the aspiration pipes and collector main to the by-product plant where they are processed for the separation of fuel gases, chemicals, solid pollutants, and the like. However, during charging of an oven, the increased gas flow can overburden the ascension pipe and the charging gases tend to flow out the charging opening around and through the descending stream of coal.
As coal is charged into an oven, it tends to pile up in cone-shaped mounds each having its peak directly beneath a charging hole. When a full charge of coke is received in an oven, these peaks are leveled off by a leveling arm which is telescoped through an opening in the oven door; however, until they are leveled, they can reach the top of the oven chamber or even extend into the charging hole, and can restrict or block the flow of the charging gases over the top of the charge of coal to the ascension pipe at the end of the oven. The result can be a substantial build-up of pressure in pockets at the top of the charge and an increased tendency of the charging gases to flow out of the oven through the charging holes.
In addition to the unburned and partially burned volatiles in the charging gas, substantial quantities of finely comminuted coal particles and dust can be entrained in and carried back out of the oven. In the past, this mixture of gas and solid material has resulted in substantial atmospheric pollution, and various solutions to the problem have been proposed.
One solution to the charging gas emission problem has been the use of a jumper pipe carried by the larry car for connecting one or more charging holes of an oven being charged with a charging hole in an adjacent oven in which the coking process is in progress. While these devices have been effective in substantially reducing emissions, their operation has not always been entirely satisfactory or without difficulty. For example, the extreme heat encountered in the coking ovens and heating chambers can produce substantial distortion in the top wall of the battery, particularly in older ovens, making it difficult to properly align the charging pipe on all the hoppers and the jumper pipe with the charging holes in the ovens to form a gas- and air-tight flow path between the two ovens. This has resulted in the escape of emissions from the jumper pipe system into the atmosphere as well as the entrainment of atmospheric air into the gases flowing through the jumper pipe to the adjacent oven. The admission of air into the gases is highly objectionable because it promotes combustion and substantially increases the temperature in the jumper pipe. This increased temperature greatly reduces the useful life of the jumper pipe system and can affect the coking process in the adjacent or connected oven. Further, substantial quantities of air can directly affect the coking process in the adjacent oven by burning the combustible gases generated in that oven. Also, an excessive burden can be placed on the aspiration system of the adjacent oven as a result of the additional gases produced.